1. Field of the Invention
The present invention relates to a check-out device for reading an article code recorded on an article in a machine readable form, and performing registration of sold articles on the basis of the read article code and, more particularly, to a check-out device wherein a customer takes part in reading of an article code.
2. Description of the Related Art
FIG. 1 shows a conventional check-out device which is equipped as a self-service check-out counter in, e.g., a supermarket. A customer CSR puts articles he or she wants to purchase in a shopping cart, carries them to this counter, and depresses a start button on an operation panel 12 so as to start registration of the articles. Thereafter, the customer CSR picks up each of the articles from the cart, and sets the article in front of an article code reader or scanner 11 to input an article code affixed thereto by means of a scanning operation of the scanner 11, and puts the read article on an entry conveyor 21 provided over an electronic weigh scale 22. The scanner 11 optically scans the article to read the article code thereof, and supplies the read article code to an electronic cash register 31. The electronic weigh scale 22 measures the weight of the article put on the entry conveyor 21, and supplies a result of the measurement as measured weight data to the electronic cash register 31. The cash register 31 has an article data table containing article data of all the articles for sale, each of which is constituted by an article code, article name data, price data, and reference weight data, for example. The electronic cash register uses the read article code, the measured weight data, and the article data table to determine that the article whose article code is read by the scanner 11 is certainly put on the entry conveyor 21, and also uses the read article code to register the article as a sold article after the determination. On the other hand, the article is fed from the entry conveyor 21 to an outfeed conveyor 41 after the determination, and further fed to a bagging area by means of the outfeed conveyor 41 and an inclined chute 42. After scanning of all the articles to be purchased, the customer CSR depresses a stop button to finish the article registration. When the article registration is finished, the electronic cash register 31 performs settlement for the sold articles on the basis of the article data stored in the article data table. A cashier CHR informs the total amount of the sold articles obtained in the settlement to the customer CSR, and stores the cash paid by the customer CSR in a drawer of the cash register 31. After the payment, the customer puts the articles stocked on a bagging area 51 into a bag, and brings them home.
FIG. 2 shows the operation of the cash register 31, which operation is performed every time the scale 22 measures the weight of an article. In this operation, in step ST1, the cash register 31 receives the measured weight data supplied from the scale 22. In step ST2, the cash register 31 receives output data from the scanner 11 as an article code. It is then checked in step ST3 if the article code is correct. If YES in step ST3, the measured weight data is compared with reference weight data of an article specified by the received article code in step ST4. If the two weight data coincide with each other, article data of the specified article is registered as a sold article using the received article code in step ST5. The entry conveyor 21 often receives an article whose article code cannot be normally read by the scanner 11, an article whose article code is not input by a customer, or an article other than an article whose article code is read. In this. case, the cash register 31 stops the entry conveyor 21 in step ST6, drives the entry conveyor 21 in the reverse direction to return the article to the customer in step ST7, and then causes the operation panel 12 to display a message for urging the customer to re-input the article code of the returned article in step ST8.
In the above-mentioned check-out device, the customer performs an input job of an article code using the scanner 11, and the cashier performs a settlement job for the customer who completes the input job of the article code. For this reason, the customer does not wait for the end of jobs of the cashier without doing anything, and the load on the cashier can be reduced. In addition, since the scanner 11 is utilized, an input error of an article code caused by a key operation error can be prevented. As a result, customers can be prevented from forming a long queue at a check-out counter. Furthermore, whether or not the article whose article code is read is the same as that on the entry conveyor 21 can be checked by comparing the weight data, thereby preventing a dishonest practice of a customer. Published Unexamined Japanese Patent Application No. 61-46591 and Published Examined Japanese Patent Application No. 1-52794 disclose systems similar to the above-mentioned check-out device.
However, this check-out device has not become so popular for various reasons.
1) The entry conveyor 21 is continuously operated to attain a quick check-out job. This means a waste of electric power in a non-busy hour. Since the entry conveyor 21 is always in sliding contact with the electronic scale 22, its service life expires in relatively a short period of time. As for the electronic scale 22, it must have a complex structure for precisely measuring the weight of an article put on the entry conveyor 21 regardless of the position of the article. This increases the manufacturing cost of the check-out device. Furthermore, this check-out device drives the entry conveyor 21 in the reverse direction when a non-coincidence of the weight of an article is detected. This results in not only an increase in manufacturing cost due to complicated control, but also disturbance against a quick check-out job. The entry conveyor 21 is driven in the reverse direction even when the non-coincidence of the weight of an article is detected upon, e.g., falling down of an article. In this case, an honest customer may have an unpleasant experience.
2) In the above-mentioned check-out device, since the electronic scale 22 is in sliding contact with the entry conveyor 21, a weight difference, with which the electronic scale 22 can identify articles with high precision, is limited. For example, articles such as bottled wines are sold to have a wide variety of stocks from inexpensive ones to expensive ones. However, since such articles do not have a difference in total weight, the following dishonest practice may occur. That is, the article code of an inexpensive wine is read by the scanner 11, and an expensive wine having substantially the same weight as that of the inexpensive wide is put on the entry conveyor 21. The conventional check-out device cannot detect the non-coincidence of the weight data items of the article in this case, and causes a loss on the side of the shop. In order to prevent such a dishonest practice, a cashier must monitor a customer's job. For example, when two readers 11 are arranged for a cashier, they impose a heavy load on the cashier.
3) During conveyance of an article, it may be replaced with another article. This replacement may be prevented by arranging a tunnel for enclosing a convey path. However, this countermeasure requires an installation space for the tunnel, and increases the manufacturing cost upon an increase in equipment scale.
4) The article data table in the cash register must contain reference weight data of all the articles for sale. However, a job for inputting the reference weight data requires relatively much time and labor.
5) In some supermarkets, a customer is instructed to carry an article returned by the entry conveyor 21 to a cashier, and the cashier registers the returned article. When many articles are returned, the customer must use a cart or basket to carry them. In this case, it may take time for him or her to put them into the cart or basket, or he or she may drop the article. Even if the cashier is allowed to drive the conveyors 21 and 41, it may similarly take time for the cashier to put many articles on the entry conveyor 21, or he or she may drop the article. As a result, a quick check-out job is disturbed.
6) The above-mentioned check-out device may accept restricted articles such as cigarettes and liquors which must not be sold to minors, and rod-shaped or wet articles which are not suitable for conveyance. Therefore, a cashier must check whether a customer wishes to purchase such article.
7) The conveyor speed must be preset as high as possible in order to shorten the required time for checking out. However, the preset speed can not cope with an increase in sales articles. For example, an unsteady glass product is easily fallen down and broken or cracked during conveyance. If the glass product is a vessel for receiving liquid, the liquid will be leaked from the vessel at this time. Further, the weigh scale 22 cannot weigh all the articles constantly with high precision when they are conveyed at a high speed. In other words, the weighing results of some articles are not reliable due to the characteristic of the scale 22.
8) The zero-point setting of the scale 22 is performed when the power of the check-out device is applied. At this time, if an empty basket is on the entry conveyor 21, the scale 22 is set at a wrong zero point according to the load weight thereof.